Catalyst-Free Growth of Graphene by Microwave Surface Wave Plasma Chemical Vapor Deposition at Low Temperature

Catalyst-free graphene films has been synthesized by microwave (MW) surface wave plasma (SWP) chemical vapor deposition (CVD) using hydrogenated carbon source on silicon substrates at low temperature (500℃). The synthesized process is simple, low-cost and possible for application on transparent electrodes, gas sensors and thin film resistors. Analytical methods such as Raman spectroscopy, transmission electron microscopy (TEM) and four points prove resistivity measurement and UV-VIS-NIR spectroscopy were employed to characterize properties of the graphene films. The formation of multilayer of graphene on silicon substrate was confirmed by Raman spectroscopy and TEM. It is possible to grow graphene directly on silicon substrate (without using catalyst) due to high radical density of MW SWP CVD. In addition, we also observed that the hydrogen had significant role for quality of graphene.

Axial uniformity diagnosis of coaxial surface wave linear plasma by optical emission spectroscopy

The coaxial surface wave linear plasma with preeminent axial uniformity is developed with the 2.45 GHz microwave generator.By optical emission spectroscopy,parameters of the argon linear plasma with a length over 600 mm are diagnosed under gas pressure of 30 and 50 Pa and different microwave powers.The spectral lines of argon and Hβ(486.1 nm)atoms in excited state are observed for estimating electron excitation temperature and electron density.Spectrum bands in305–310 nm of diatomic OH(Σ-Π+A X22 i)radicals are used to determine the molecule rotational temperature.Finally,the axial uniformity of electron density and electron excitation temperature are analyzed emphatically under various conditions.The results prove the distinct optimization of compensation from dual powers input,which can narrow the uniform coefficient of electron density and electron excitation temperature by around 40%and 22%respectively.With the microwave power increasing,the axial uniformity of both electron density and electron excitation temperature performs better.Nevertheless,the fluctuation of electron density along the axial direction appeared with higher gas pressure.The axial uniformity of coaxial surface wave linear plasma could be controlled by pressure and power for a better utilization in material processing.

Electrostatic Surface Modes in Magnetized Quantum Electron-Hole Plasma

The excitation of electrostatic surface waves on a semibounded quantum plasma-vacuum interface parallel to an applied magnetic field with electron-hole degeneracy is investigated. The wave equations of the electrostatic potential and both of the perturbed electron and hole plasma densities have been solved analytically. By using quantum hydrodynamic (QHD) model and the Poisson’s equation with appropriate boundary conditions, the general dispersion relation of these surface modes has been obtained. It is also solved and studied numerically for different cases of plasmas (magnetized or unmagnetized, classical or quantum). We have found that the density ratio of hole-electron plasma plays essential role on the dispersion of the modes along the wavelength beside the quantum and magnetic field.

表面波等离子体暴露下铜表面的氧化特性(英文)

Surface wave plasma(SWP) is a kind of low temperature plasma which can be utilized for material development.In this research,argon and oxygen were used as a working gas for an SWP experiment and the influence of the plasma irradiation on a copper surface was examined.Particular,relation between the spatial characteristics of SWP and wetting characteristics was examined.As a result,it was found that spatial characteristics of the SWP affected the wetting characteristics and the oxidation characteristics.